1. Field of the Invention
The present invention relates to an anthracene derivative compound and an organic light-emitting device including the same. More particularly, the present invention relates to an anthracene derivative compound that has good electrical characteristics, and when applied to an organic light-emitting device, can offer excellent driving voltage, efficiency, and color purity characteristics, and an organic light-emitting device employing an organic layer including the anthracene derivative compound.
2. Description of the Related Art
Organic light-emitting devices are active emission display devices that emit light by recombination of electrons and holes in a thin layer (hereinafter, referred to as “organic layer”) formed of a fluorescent or phosphorescent organic compound when a current is supplied to the organic layer. The organic light-emitting devices have advantages such as lightness, simple constitutional elements, easy fabrication process, superior image quality, and wide viewing angle. In addition, the organic light-emitting devices can perfectly create dynamic images, achieve high color purity, and have electrical properties suitable for portable electronic equipment due to low power consumption and low driving voltage.
Eastman Kodak Co. has developed an organic light-emitting device with a multi-layered structure including an aluminum quinolinol complex layer and a triphenylamine derivative layer (U.S. Pat. No. 4,885,211), and an organic light-emitting device including an organic light-emitting layer formed of a low molecular weight material capable of emitting light in a broad wavelength range from UV to infrared light (U.S. Pat. No. 5,151,629).
Light-emitting devices are self-emitting devices and have advantages such as a wide viewing angle, good contrast, and a rapid response time. Light-emitting devices are classified into inorganic light-emitting devices using an emitting layer formed of an inorganic compound and Organic Light-Emitting Devices (“OLEDs”) using an emitting layer formed of an organic compound. OLEDs show better brightness, driving voltage, and response speed characteristics and can create polychromatic light, compared to inorganic light-emitting devices, and thus, extensive research into OLEDs has been conducted.
Generally, OLEDs have a stacked (i.e., layered) structure having in sequence an anode, an organic light-emitting layer, and a cathode. OLEDs may also have various, more specific structures such as anode/hole injection layer/hole transport layer/emitting layer/electron transport layer/electron injection layer/cathode structure or an anode/hole injection layer/hole transport layer/emitting layer/hole blocking layer/electron transport layer/electron injection layer/cathode structure.
Materials used for OLEDs can be classified generally as either vacuum-depositable materials and solution-coatable materials according to an organic layer formation process. Vacuum-depositable materials must have a vapor pressure of 10−6 torr or more at 500° C. or less, and may be low molecular weight materials having a molecular weight of 1,200 g/mol or less. Solution-coatable materials must have solubility sufficient to form solutions, and can include those materials incorporating an aromatic or heterocyclic ring.
When manufacturing OLEDs using a vacuum deposition process, manufacturing costs may increase due to use of a vacuum system, and it may be difficult to manufacture high-resolution pixels for natural color displays using a shadow mask. On the other hand, when manufacturing OLEDs using a solution coating process, such as, for example inkjet printing, screen printing, or spin coating, the manufacturing process is simple, manufacturing costs are low, and a relatively high resolution can be achieved for the pixels when compared to those prepared using a shadow mask.
However, when using solution-coatable materials, the performance (e.g., thermal stability, color purity) of light-emitting molecules is lowered compared to when using vacuum-depositable materials. Even though the light-emitting molecules of the solution-coatable materials have good performance, there arise problems that the materials, when formed into an organic layer, gradually crystallize and grow into a size that is comparable to visible light wavelength range, and thus, such crystals scatter visible light, thereby causing an observable turbidity phenomenon, and pinholes, and other defects, may be formed in the organic layer, thereby causing device degradation.
Japanese Patent Laid-Open Publication No. 1999-003782 discloses a 2-naphthyl-substituted anthracene compound that can be used in an emitting layer or a hole injection layer. However, OLEDs employing the anthracene compound are unsatisfactory in terms of driving voltage, brightness, efficiency, and color purity characteristics, and thus, there is room for improvement in conventional OLEDs.